Diagnosing iron deficiency in narrow-leafed lupins

Lupin crops grown on fine-textured, alkaline soils that become saturated with water in winter will usually show bright yellowing of young leaves that is typical of iron deficiency.

Smaller paler plants with chlorotic new leaves

Deficient leaves (above) are uniformly pale

New growth is most affected

What to look for

Paddock

Smaller paler plants with chlorotic new leaves.
Deficiency is most likely in deep pale or limed sands, and in waterlogged areas.

Plant

Young leaves and new growth become yellow over the whole leaf.
As deficiency often occurs in wet conditions, brown leaf spot lesions on leaves may also be be present.
Middle leaves of severely deficient plants may shrivel back towards the base of the leaflet

Where did it come from?

Soil type

Soil type

Temperature

Temperature

There are a complex series of interactions in the soil that combine to reduce the availability of iron to lupins. The deficiency will usually occur in lupin grown on soils with a pH above 7.0 if the soil aeration is reduced slightly and temperatures are cold.

Management strategies

Spraying foliar

Spraying foliar

No yield responses to iron have been measured in the field to justify soil application.
Foliar sprays will remove the symptoms where they occur in highly calcareous or limed soils
Where symptoms occur, particularly in cold and wet conditions, they are frequently eliminated by increased soil and air temperatures.

Further information

Plant nutrition [1]

Links
[1] https://www.agric.wa.gov.au/crops/production-postharvest/plant-nutrition

Important disclaimer

The Chief Executive Officer of the Department of Primary Industries and Regional Development and the State of Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it.